Electrically heated appliance



Feb. 1, 1955 c. A. CRAWFORD ELECTRICALLY-HEATED APPLIANCE 2 Sheets-Sheet1 Original Filed Aug.. 18, 1947 INVENTOI. 62m? 4. (aw-0K0 ATTORNEY.

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United States Patent ELECTRICALLY HEATED APPLIANCE Clark A. Crawford,Painted Post, N. Y., assignor to Corning Glass Works, Corning, N. Y., acorporation of New York Original application August 18, 1947, Serial No.769,102, now Patent No. 2,609,478, dated September 2, 1952. Divided andthis application August 1, 1952, Serial No. 302,123

8 Claims. (Cl. 219-43) The present invention relates to an electricallyheated appliance having its heating element integral therewith anddesigned for use with an associated, circuit-controlling supporttherefor. This application is a division of application Serial No.769,102 filed August 18, 1947 by Anthony Miller and myself, now PatentNo. 2,609,478 issued September 2, 1952.

In general, the prime object of the invention is a device of theforegoing character which will efliciently perform the purposes forwhich it is intended, which is simple and economical of construction,and which can be expeditiously, conveniently, and safely manipulated.

Another object is a cordless electrical cooking utensil which can bewashed without danger of detrimental effect to the heating element.

A still further object is an electric percolator capable of brewingcoffee at an extremely rapid rate.

Further objects and features of the invention will become apparent froma further perusal of this specification when considered in connectionwith the accompanying drawings forming a part thereof.

In the accompanying drawings:

Fig. 1 is a side elevation, partly in section, illustrating a coffeepercolator embodying the invention and a support therefor.

Fig. 2 is a fragmentary view of Fig. 1 taken on line 2-2.

Fig. 2a is an enlarged view, in section, of a fragment of thepercolator.

Fig. 3 is a top plan view of the greater part of the base of theassembly.

Fig. 4 is a sectional elevation taken on line 4--4 of In brief, theinvention as illustrated comprises a glass percolator having a vessel 1,pump 2, basket 3, and cover 4, adapted for use with a support or stand20. The vessel differs from conventional forms in that it has a raised,conical-shaped bottom, the wall 5 having a domeshaped top 6. The base ofthe conical bottom wall portion 5 is joined to a surroundingsubstantially horizontally disposed bottom portion 7 whose periphery isin turn joined to the surrounding side wall 9.

The underside of portions 5-7 is provided with an electricallyconductive coating 10 integrally attached to the glass. In order toprevent the watt density or heat input per unit of area from increasingexcessively as the center of the area is approached, the conductivecoating is so distributed that its electrical resistance per unit ofarea increases as the distance from center increases. This isaccomplished by properly grading the coating thickness. Putting itanother way, the coating is so distributed that its thickness, and henceits conductivity, increases as the distance from the periphery of thecoated area increases.

The peripheral portion of coating 10 is provided with a terminal 11comprising a low-resistance metallized coating in the form of a flatcircular band. Centrally disposed on the coating 10 is a similarlow-resistance coating 11' to which is attached, by soldering forexample, a terminal 12 having a depending prod or post 13.

A suitable abrasion-resistant electrically conductive coating may beproduced by spraying the vessel, while heated, with tin chloride orother tin salt. The lowresistance terminals may be formed by applying asilver metallizing composition and firing it on the glass in knownmanner.

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The pump 2 has a support portion 16 of the general configuration of thevessel parts 5 and 6, and is of such size that when resting on thevessel bottom there is approximately one-eighth inch space between theopposing surfaces of the vessel and pump support portions. The bottomedge portion 17 of the pump is not provided with serrations, theperfectly plain usual manufacturing irregularities in portion 17 and theadjoining bottom surface of portion 7 of the vessel providing amplespace for the passage of fluid from the vessel 1 into the space betweensupport portion 16 and vessel portions 5 and 6.

The vessel support 20 contains an element 21 of electrical insulation,carried on a circular base portion 22, and comprising a centralupstanding or conical portion 23 and a surrounding flat portion 24.Portion 23 has an aperture or passage 25 (Fig. 4) therethrough, andportion 24 has apertures or passages 26 and 27 therethrough. A sleeve 30passing through aperture 25 is securely clamped between the enlarged end31 of sleeve 30 and a clamping washer 32. Arranged on sleeve 30 betweenwasher 32 and a clamping nut 33 is an insulating sleeve 34 about whichare arranged a series of flat springs 41-44. Springs 41 and 42 directlyengage one another, whereas springs 4244 are insulated from one anotherby suitable spacer washers 4648. Spring 41 at its opposite end carrieselectrodes 49 and 50 which project up through apertures 26 and 27respectively. Springs 42 and 44 are bent to bring their free ends 52 and54 in position to be electrically connected to one another by a metalwasher 55 supported on an insulator 56 carried on a plunger electrode57, and spring 43 is bent to bring its free end 53 directly underelectrode 57.

The plunger electrode 57 within the sleeve 30 is surrounded by a spring60 compressed between an enlarged portion 61 of the electrode and aninturned flange 62 of the sleeve, and accordingly spring 60 tends tomove electrode 57 up. This movement is restricted by a stop washer 64prevented from moving down on the electrode by the end 65 of a spring 63which passes through an aperture 66 in electrode 57. Spring 63 isthreaded on electrode 57 and is held in a compressed state betweenflange 62 and insulator 56 by a pin 58 passing through the electrode,and serves to enable downward movement of the plunger into contact withspring end 53 after washer 55 engages the relatively rigid contactspring ends 52 and 54.

Incoming conductors 71 and 72 are at one end connected to springs 43 and44, and at their other end terminate in a conventional attachment plug73 for connection with any available current source.

As will be clear from an inspection of Fig. 4, when the support 20 isunoccupied, no electrical connection exists between springs 44 and 42,or between spring 43 and electrode 57, and accordingly exposure ofelectrodes 49, 50 and the shielded end 57 of electrode 57 presents noshock hazard. Furthermore, because of the shielded position of the topor exposed end 57' of electrode 57, danger of inadvertent depressionthereof far enough to connect a potential to the electrodes 49, 50 and57 is prevented. When, however, the vessel is placed on the support 20,prod 13 engages and lowers electrode 57 into engagement with spring end53 and hence into electrical connection with conductor 71. As electrode57 is being lowered, the metal washer 55 bridges spring ends 52 and 54to electrically connect conductor 72 with spring 42 and accordingly withspring 41, and electrodes 49 and 50.

The springs 41 and 60 are so tensioned that a compressive force equal tothe weight of the vessel, pump, basket and cover, plus fluid to a levelat least to the top of the dome, is required to compress them to theiroperative positions as shown in Figs. 1 and 2, so that if the liquidboils away below this level, the vessel will be automatically raised andelectrical connection to its heating element interrupted.

Although the invention has been shown applied to a coffee maker of aparticular type, it will be appreciated that various features thereofmay be incorporated in other forms of electrically-heated deviceswithout departing from the spirit and scope of the invention as claimed.

The combination of an electrically heated device of the above type andthe above support therefor is claimed in the above-indicated applicationof Anthony Miller and myself, together with the support per se.

What is claimed is:

1. In a cofiee maker, a vessel having a bottom which comprises a centralportion of generally conical configuration, surrounded by a relativelyfiat band area connecting the central portion of the bottom with thevessel sidewall, an electric heating element in the form of a thin filmof conductive material spread over and wholly blanketing that exteriorsurface of the vessel which is of conical configuration, and a pumpwithin the vessel including a base of conical configuration supported onthat bottom area of the vessel between the conical bottom portion andthe vessel side wall and having its underside spaced an average distanceof between one-eighth and one-fourth inch from the oppositely disposedconical bottom surface of the vessel.

2. In combination, a glass container, an electricallyconductive coatingcovering a circular bottom area of said container, and low resistanceterminals for connection with an electrical current source joined tosaid coating, one of said terminals covering the central area of saidcoating and one of said terminals being in the form of an endless bandand joined to the peripheral portion of said coating.

3. A combination such as defined by claim 2 wherein the coated portionis of generally conical configuration and is surrounded by an annularflange portion joined at its periphery to the container side wall.

4. In combination, a container having a bottom comprising a centralportion of generally conical configuration surrounded by an annularflange portion joined at its periphery to the container wall, a coatingof electricallyconductive material covering and bonded to that surfaceof the conical portion outside thecontainer and constituting an electricheating element therefor, and terminals for said element bonded to thecentral area of the coating and to the bordering portion thereofrespectively.

5. In an electric coffee maker, a vessel having an upwardly extendinggenerally hollow cone-shaped bottom with the apex of dome configuration,a conductive coating spread over the surface of the vessel bottomconstituting the inner surface of the cone, a low electrical resistanceterminal bonded to said conductive coating in the central area thereof,and a second low electrical resistance terminal bonded to said coatingalong its bordering area.

6. A glass coffee-maker bowl having a bottom with an upwardly extendinggenerally cone-shaped portion whose base is joined to a substantiallyhorizontally disposed surrounding portion, a conductive coating bondedto the underside surface of the cone and extending over the majorportion of the surface area of the surrounding portion, andlow-resistance terminals bonded to said coating, one of said terminalsbeing located on the uppermost under-surface area of the cone and onebeing in the form of a circular band connected to the peripheral portionof said coating.

7. The combination such as defined by claim 2, wherein the thickness ofthe coating is so distributed that its resistance per unit of surfacearea increases as the distance from the central area increases.

8. The combination such as defined by claim 4, wherein the electricallyconductive material is distributed more thickly as the distance from thebordering portion thereof increases.

References Cited in the file of this patent UNITED STATES PATENTS799,377 Harden Sept. 12, 1905 2,020,364 Lehmann Nov. 12, 1935 2,021,661Kisfaludy Nov. 19, 1935 2,054,714 Reich Sept. 15, 1936 2,081,894 Meyeret al May 25, 1937 2,119,680 Long June 7, 1938 2,266,090 Smith Dec. 16,1941 2,378,772 Hummel June 19, 1945 2,429,420 McMaster Oct. 21, 19472,431,998 Ely Dec. 2, 1947 2,434,560 Gunter Jan. 13, 1948 2,475,379Strong July 5, 1949 2,609,478 Crawford et al Sept. 2, 1952 FOREIGNPATENTS 921,934 France Jan. 20, 1947

